Machine Type Communication (MTC) user terminal (referred to as user equipment or terminal), also called Machine to Machine (M2M) user communication device, is one of main application forms of the present Internet of Things. In recent years, due to high spectral efficiency of Long-Term Evolution (LTE) systems/Long-Term Evolution Advance (LTE-Advance, LTE-A) systems, more and more mobile operators choose LTE/LTE-A as an evolution direction of broadband wireless communication systems. Multiple LTE/LTE-A-based MTC data services will be more attractive.
Related LTE/LTE-A systems perform transmission based on dynamic scheduling of each subframe, i.e., each subframe can transmit a different control channel, a frame structure of which is shown in FIGS. 1 and 2.
FIG. 1 is a schematic diagram of a frame structure of a Frequency Division Duplexing (FDD) mode in accordance with the related art. As shown in FIG. 1, a radio frame of 10 ms consists of twenty slots numbered 0˜19 with a length of 0.5 ms, slots 2i and 2i+1 forming a subframe i with a length of 1 ms, wherein i is 0 or a nature number.
FIG. 2 is a schematic diagram of a frame structure of a Time Division Duplexing (TDD) mode in accordance with the related art. As shown in FIG. 2, a radio frame of 10 ms consists of two half frames with a length of 5 ms, a half frame including 5 subframes with a length of 1 ms and subframe i being defined as 2 slots 2i and 2i+1 with a length of 0.5 ms.
The Physical Downlink Control Channel (PDCCH) and enhanced Physical Downlink Control Channel (ePDCCH) are defined in the LTE/LTE-A. Information carried by the Physical Control Format Indicator Channel (PCFICH) is used to indicate the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols which transmit the PDCCH in a subframe. The Physical Hybrid-ARQ Indicator Channel (PHICH) is used to carry acknowledgement/negative acknowledgement (ACK/NACK) feedback information of uplink transmission data, wherein ARQ is an abbreviation of Automatic Repeat-reQuest.
The PDCCH used to carry Downlink Control Information (DCI) includes uplink and downlink scheduling information and uplink power control information.
Generally, a MTC terminal can obtain the DCI by demodulating the PDCCH/ePDCCH in each subframe in order to achieve demodulating of the Physical Downlink Share Channel (PDSCH) and scheduling indication information of the Physical Uplink Share Channel (PUSCH).
Among MTC application terminals, there is a kind of terminals, coverage performance of which decreases significantly due to their positions or the limitation of their own characteristics. For example, MTC terminals of an intelligent meter reading type mostly are installed fixedly under a low coverage performance environment, such as in a basement, mainly send small packet data, and therefore have a low demand for data rate and are able to tolerate greater data transmission delay. Because of such terminals' low demand for data rate, for data channels, correct transmission of the small packet data can be ensured by lower modulating code rate and multiple repeated transmissions in time domain; for synchronization channels, information sent by base stations is same, so it is enough for the terminals to receive the same information sent by multiple subframes. For control channels, the method of which multiple subframes sending the same DCI repeatedly is not supported at present.